WELCOME TO THE WORLD OF DIGITIZATION

Hey friends and Techies,

Welcome to the world of digitization... Here you will find all the support, updates and technical solutions regarding the digital televisions, headend, OTT and IPTV as well. All the issues related to set top boxes, LNB, DVB, CAS, PSI-SI etc... You are at the right place. Here we will try to cover all the aspects of Digital headend, the working of the Set top boxes, how the industry is changing and moving towards new technologies like OTT, UHD, 4K Television, new government rules applicable in the compliance related to these and lots more.

All the comments and queries are most welcome. I would love to discuss about these technologies in the comment sections here.

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PSI-SI story

For the customer, turning on the STB and watching the channel is as easy as ABC, just turn it on and switch to your favorite channel and that is it. But wait… Is it that simple? How does the STB know which channel is on that LCN and how do they display those channel name and the EPG list?

To answer all these, we have got something in the backend/headend system which is PSI-SI system.

So what is PSI-SI system? In broader terms PSI refers to Program Specific Information and SI refers to Service Information. 

PSI was standardized by MPEG system while SI was added to it by DVB.

PSI contains 4 Tables namely PAT, CAT, PMT and NIT.

PSI is carried in the form of a table structure. Each table structure is broken into sections. Each section can span multiple transport stream packets. On the other hand, a transport stream packet can also contain multiple sections with same PID.

So let us break this PAT, CAT, PMT and NIT now.

PAT: Program Association Table
This table lists all the services found in this Transport Stream. Each Transport stream contains only one PAT. Each service is identified by a PMT.
The PAT is always on PID 0.

PMT: Program Map Table
This table identifies all the Elementary Streams within a service. A service is uniquely identified by its service ID.There is one PMT per service, but there may be more than one PMT on the same PID. The PMT contains the ES like Video, audio, ECM, Teletext and so on.

NIT: Network Information Table
Although the existence of this table is specified in MPEG, its contents and use are specified by the DVB below in the SI. 

CAT: Conditional Access Table
This table controls the scrambling and authorization of a service. It associates one or more CA systems with their EMM (Entitlement Management Message) stream and any other extra data that may be required. CAT is always on PID 1.

This sums up the PSI table. Now let’s find out about SI.
SI tables contains 8 Tables and is standardized by DVB. These tables are:

NIT, SDT, BAT, EIT, TDT, TOT, ST and RST.

NIT: Network Information Table
The Network Information Table groups a number of Transport Streams together providing tuning information for the STB. If a user can view a service via two different delivery mechanisms then each mechanism will have a different Network ID. Hence NIT actual will be an essential and mandatory Table and a Transport Streams can have many NIT others.
NIT contains the delivery mechanism be it cable, satellite or terrestrial, The tuning parameters of the STB such as frequency, Symbol rate, home transport information and other private descriptor such as OTA information, telephone numbers etc. The NIT PID is 16.

BAT: Bouquet Association Table
A Bouquet is a group of services which are presented to the user as though they were on the same Transport Stream. The user may select different services within the bouquet, but be unaware that the STB is in fact re-tuning its input to pick up a new transport stream within the network or from different networks as well. The LCN for every services can be defined here.

SDT: Service Description Table
A description of a service provides a name and optionally other related information such as language codes, running status and country availability. There may be several sub tables providing information for this Transport Stream and other Transport Streams within the bouquet /network. SDT actual is a mandatory table for tuning the STB and for the TS to know the information about other TS, SDT other is defined.

EIT: Event Information Table
This forms the basis of a database upon which an Electronic Program Guide may be based.
Present/Following information allows events on a service to be classified as running, not running,paused and starts in a few seconds. Schedule information is arranged by table, sub-table, segment and section into 3 hours blocks within which the program guide information can be transmitted. In general, the EIT information may be scrambled, although different countries may provide regulations which restrict this practice.

TDT: Time and Date Table
Provides UTC (Universal Time) coded as MJD (Modified Julian Date)

TOT: Time Offset Table
Is used to provide time offsets to give local time. This is required to show the proper time in the STB display.

RST: Running Status Table
These are sent out only once to update the status of an event. It allow accurate and rapid updating of the timing status of one or more events.

ST: Stuffing Table
Used to replace or invalidate existing section of other tables at a delivery system boundary. It saves time and power as we don’t have to check all the packets.

Common Issues of Set top Box a customer Face and its checklist.

                     
Agh... No Signal!! STB not authorized!! Box not powering up!! Waiting for CA Table..!!

So many issues customers face when they turn on the Set top Box. Most of them don't even power cycle it for days. Here are some of the common issues for the customers with their checklist before reaching out to Operators:

1. No Signal on The Screen:
 Before you blame the STB, please check the appropriate source is selected on the TV. Most of the TV shows no signal when wrong input source is selected.
Once its checked, please check if the RF cable is properly fitted to the STB and do a power cycle of the STB. If the issue still persist please contact your cable operator as the RF cable or the optical fiber might be the culprit.

2. STB not authorized: 

Have you paid the monthly subscription fees?? If yes then please call the operator and ask him to retrigger the Set top box. If not, then the box has been deactivated due to non payment issue.

3. STB not powering up:

Please check if you are using the proper adapter provided along with the STB. Also check the Supply source if it is working with any other electronic device. Once checked, please try to pull back the adapter and put it back again and check if it is powering up. If not, please reach out to the nearest service center.

4. Channel not in sequence/ Few Channels not showing up:

This can happen in rural areas where signal strength is usually weak and hence few channels of last frequencies get skipped. Doing a factory reset might resolve the issue. Once you get all the channels, ask the operator to increase the signal strength.
                         

OTT: Changing the future of Television

OTT stands for “over-the-top,” the term used for the delivery of film and TV content via the internet, without requiring users to subscribe to a traditional cable or satellite pay-tv service. OTT is basically a unicast model with three types of revenue models that it can provide.

SVOD (subscription-based services such as Netflix, Amazon and Hulu)

 AVOD (free and ad-supported services such as Crackle)

 TVOD (transactional services such as iTunes, Vimeo on Demand and Amazon Instant Video that allow users to pay for individual pieces of content).

So now we are going to talk about the technology that brought revolution in the internet TV platform that is Adaptive bitrate streaming over HTTP.

Adaptive Streaming over HTTP

The traditional IPTV is just a multicast packets sent through a pipe to the customer. But with OTT, we have seen many technological advancement. Adaptive streaming is one such technology which helps for the best viewer experience. The key features of it are:

Download and Stream:

Imitation of Streaming via Short Downloads.

Downloads desired portion in small chunks to minimize bandwidth waste.

Enables monitoring consumption and tracking clients.

Adaptation to Dynamic Conditions and Device Capabilities

Adapts to dynamic conditions anywhere on the path through the Internet and/or home network

Adapts to display resolution, CPU and memory resources of the client

Facilitates “any device, anywhere, anytime” paradigm

Improved Quality of Experience

Enables faster start-up and seeking (compared to progressive download), and quicker buffer fills

Reduces skips, freezes and stutters.

Use of HTTP

Well-understood naming/addressing approach, and authentication/authorization infrastructure

Provides easy traversal for all kinds of middleboxes (e.g., NATs, firewalls)

Enables cloud access, leverages existing HTTP caching infrastructure (Cheaper CDN costs)

The above image depicts the Adaptive streaming OTT service currently being used by most of the OTT service providers.

Any content which is being pushed or pulled is shown in the production part above in the image.

Once the content is available, the OTT provider generally uses a multi bitrate encoding platform which converts the content to the desired resolution as and when required.

The content is protected by the encapsulation engine, well known as DRM (Digital rights management) system. There are many vendors which provides their DRM solution.

When it comes to the distribution network, the OTT providers uses content delivery network. We will discuss about CDN in my other publication as CDN itself is a huge topic. Basically it will get video, data, from many locations and maintain the high availability so that user doesn’t have to compromise if one of the production location is down.

The next stage is the consumption which is a user interface. Be it a TV, desktop, laptop, tablets or smartphones, The OTT provider has one solution for it. With the ABR streaming, customer will have a seamless experience with all his devices without compromising the screen resolution or worrying about the internet bandwidth.

So to summarize, the next gen customers are looking for a revolution in TV industry and the OTT is the best bet for the service providers.